1. Field of the Invention
The present invention relates to a hydraulic apparatus for an automatic transmission, and in particular, to the structure of an oil strainer arrangement.
2. Description of the Related Art
Conventionally, for example, in providing an oil strainer as shown in Japanese Laid Open Patent No. Sho-58-44006, a metal sheet is subjected to a stamping process to form a dish-shaped base member with a peripheral edge shoulder section and a flat wall section having a large number of supporting bosses. Mounted onto this dish-shaped base member is a filter element having a fiber mesh securely mounted to a filter frame with a plurality of ribs.
This strainer has a flat shape and is housed in an oil pan secured on the bottom of a transaxle casing. The oil in the oil pan is sucked into the oil strainer through a filter element, passes through a flow channel made up of the spaces formed from the ribs of the filter frame and the supporting bosses of the dish-shaped base member and is conducted to a discharge port.
However, in the case where an oil strainer of the above construction is positioned in an automatic transmission without an oil pan in the lower part of the device, it is not possible to ensure sufficient space to provide a supporting member and space for installing the flat strainer. The problem of intalling the strainer is created and when maintenance of the strainer are to be performed, the casing must be disassembled, so a problem is also created in the maintenance of the strainer.
Accordingly, as shown in FIG. 6 to FIG. 8, in an automatic transmission mounted in an FF (Front Engine, Front Drive) vehicle, a valve body 26 is provided on the side of the automatic transmission, a certain space 6' is formed on the lower part of a transaxle casing 13', and an intake opening 6a communicating with an oil sump 9' is provided in a circumferential wall portion in the space 6' for convenience in arranging the parts mounted on the vehicle. In addition, an oil strainer 2' is provided in the space 6', and to allow the oil strainer 2' to be removed without disassembling the casing, the space 6' is tightly sealed by the installation of a cover member 7' and communicates with the oil pump from the oil sump.
However, in the abovementioned hydraulic device, because the intake opening is directly formed in the transaxle casing, and whenever the mounting angle of the automatic transmission is changed, the position of the oil sump must also be changed, but it is not possible to freely change the position of the intake opening. As a result, it is not possible to easily accommodate the diversification of the mounting angle of the automatic transmission which has accompanied the recent trend toward many different varieties of vehicles.